Nitration of alcohols



Patented Nov. 16, 1948 NITRATION OF ALCOHOLS Arthur Ernest Wilder Smith, Wallingford,

Charles William Scaife, Norton-on-Tees, and Harold Baldock, deceased, late of Norton-on- Tees, England; by Herbert Baldock, legal representative, Hoylake, England, assignors to Imperial Chemical Industries Limited, a corporation of Great Britain 4 No Drawing. Application October 15, 1945, Serial No. 622,487. In Great Britain October 27, 1944 8 Claims. (01. 260- 467) This invention relates to the nitration of alcohols, particularly of nitro-aliphatic alcohols, to give esters.

The nitration of monohydric, dihydric and trihydric alcohols and of nitro-alcohols by means of mixed nitrating acid or by nitric acid to give the esters is known. Both methods suffer from disadvantages: the former in that recovery of mixed acids is necessary and separation of the reaction products is troublesome; the latter in that serious oxidation and conversion of nitric acid to nitric oxide occur, and recovery of the diluted nitric acid is not economic. It is an object of the present invention to provide a process which economises in nitrating agent, in which a complex recovery system is unnecessary and in which the alcohol esters are obtained in a readily separable form.

According to the present invention there is provided a process for the production of the nitric acid esters of alcohols which comprises reacting at least one alcohol with nitrogen tetroxide in the liquid phase. Preferably the reaction is carried out in the presence of oxygen, or a gas, for example air, containing oxygen, as economy in nitrogen tetroxide and improved efiiciency are thereby obtained. An advantage connected with the use of nitrogen tetroxide as nitrating agent is that it is unnecessary to drown the reaction products in water. The process of the invention is of particular value in relation to the nitration of the nitro-aliphatic mono-alcohols because in their case the disadvantages and advantages mentioned in the immediately preceding paragraph particularly apply.

On acccunt oi the better yields, improved efficiency, simpler manipulation, and easier separation of the esters, it is preferred to employ substantially pure nitrogen tetroxide, but it is also possible, although not with so good results, to employ nitrogen tetroxide produced in situ, from mixtures of nitrogen trioxide or nitric oxide with air or oxygen. Moreover, it is well known (Ephraim and Thorne: Test Book of Inorganic Chemistry: English Edition, 1926: p. 572) that nitrogen trioxide exists at only very low temperatures and that it behaves otherwise as a mixture of nitric oxide and nitrogen tetroxide. In general, therefore, nitrogen trioxide contains substantial amounts of nitrogen tetroxide, and this, we have found, is effective as a nitrator in the process of the present invention. It is therefore to be understood that the use as nitrator, in the process of the present invention, of nitrogen tetroxide contained in or obtained from nitrogen 2 tetroxide in this manner, and therefore also of so-called nitrogen trioxide which contains nitrogen tetroxide, falls within the scope of the invention.

The reaction, which may be carried out under various conditions of temperature and pressure, for example, using pressures greater than atmospheric, will generally be carried out at a temperature of not more than 20 C., more particularly at atmospheric pressure and within the temperature range 010 C. Best results are obtained using nitrogen tetroxide in considerable excess of that necessary for converting the hydroxyl content into nitrate.

The invention is of particular value for the production of the nitrate esters of nitroethanol, nitropropanol and nitrobutanol, particularly nitro tertiary butanol. Much larger yields of the last mentioned ester are obtained by the method of the present invention than by the prior method using mixed nitrating acids.

The reaction may, for example, be carried out by bubbling air or oxygen through a mixture of a nitro-alcohol and an excess of nitrogen tetroxide contained in a reaction vessel maintained at about 0-10 C. and connected by a delivery tube with a cooled catchpot. An nitrogen tetroxide carried over by the air is recovered from the catchpot. When the reaction has proceeded far enough the unchanged nitrogen tetroxide is distilled off and collected for re-use and the nitro-alcohol nitrate is obtained by washing with water or an aqueous salt solution, and distilling for example at -90 C. and 1 mm. pressure. Working in this way the nitrate of 1-nitro-ethano1-2 has been obtained in 50-60% yield and those of nitropropanol and nitro tertiary butanol in yields of 40-55%.

For example by reacting 10.5 gms. of l-nitro 2-propanol and 291 gms. of nitrogen tetroxide at 5 C. for 3 days, air being bubbled through the mixture the while, a 52% yield of l-nitropropanol-Z nitrate was obtained.

Example 15 gms. of nitro tertiary butanol was treated with '75 gms. of pure nitrogen tetroxide and a slow stream of oxygen was passed for 12 hours. After adding gms. more of nitrogen tetroxide the process was repeated. The excess nitrogen tetroxide was recovered by distillation and the remaining oil was poured on to ice. The insoluble oil was separated, washed with water, and distilled under 1 mm. pressure to give 8.0 gms. of nitro tertiary butyl nitrate.

We claim:

1. A process for the production of the nitrate esters of nitro-ethanol. which comprises reacting. nitro-ethanol with nitrogen tetroxide in the liquid phase at a temperature below 20 C.

2. A process for the production of the nitric acid esters of nitro-butanol which comprises reacting nitro-butanol with nitrogen tetroxide'inthe liquid phase at a temperature below 20 C.v

3. A process for the production 'of nitroter tiary butyl nitrate which comprises reacting-nitrotertiary butanol with nitrogen tetroxicle in. the: liquid phase at a temperature below 20 C.

4. A process for the production of the nitric acid esters of nitro-alcohols which comprises reacting in the liquid phase-a-mnno-nitro substituted mono-hydroxy alkano'l with. nitrogen; tetroxide at a temperature below 20 C.

5. A process as claimed in claim 4, wherein the temperature range is from to C.

62. Theprocess as claimed in claim 4, wherein the-proportion of nitrogen tetroxi'd'e by weight is at least five times that of the nitro-alkanol.

7. A process for the production the nitric acid esters ofnitro-alcohols which comprises-reacting amono-nitro substituted mono-hydroxy alkanol with-nitrogen tetroxide in the liquid phase at a temperature below 20 C. in the presence of a gas containing oxygen.

8. The process as claimed in claim 7, wherein the oxygen-containing gas is bubbled through the mixture.

ARTHUR ERNEST WILDER SMITH. CHARLES WILLIAM SCAIFE. HERBERT BALDOCK, Legal Representative of the Estate of Harold Baldock, Deceased.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED- STATES PATENTS Number Name Date 2,298,387 Kenyon'et a1 Oct. 13, 1942 2,330,112 Cox Sept. 21, 1943 2,424,510 Smith et a1 July 22, 1947 OTHER REFERENCES Cohen et al.: J'our. Chem. 800., vol. 71, pp. 10504057 (1897); ibid., pp. 1057-1059 (1897)..

Oddo: Gass. Chim. ItaL, v01. 45, I, pp. 413-443 (1915).

Wieland et a1.: Ber. Deut. Chem., vol. 53, pp.- 201-210 (1920).

Bass et al.: Jour. Amer.Chem. 800., vol. 46, pp. 456461 (1924).

Harris et a1.: J our. Amer. Chem. Soc., vol. 63, pp. 2520-2523 (1941 

